The present application claims priority of China Application No. 200610002331.4 filed in China on Jan. 26, 2006 under 35 U.S.C. §119; the entire contents of all are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a seal for a box. More particularly, to a seal for a box used together with an underwater mechanical apparatus for waterproofing an electronic circuit, for reinforcing heat elimination, and for displaying a water leakage condition.
2. Description of Background Art
Normally, traditional cleaning machines used in swimming pools employ a motor to power a water pump and for driving the cleaning machine. These machines usually have an output power of about 50 w˜200 w. For easy control of the functions of the machine, it is an advantage to install the electronic devices inside the body of the cleaning machine. However, the capacity of the cleaning machine is limited. In addition, the size of the container for the circuit is also limited. Even with heat-generated in an amount of 10 W, the problems will occur with regard to an increase in the temperature and plastic transmuting. In order to solve the problem of heat elimination, traditionally, a metal piece is set on the bottom of the board that is equipped with the electronic devices. Thus, as the metal piece contacts the water in the swimming pool, the heat will be eliminated. Another method is to increase the size of the container for placing the circuit board, thus to increase the cross-ventilation for reducing the temperature.
In some countries or regions with plentiful sunshine throughout the year, the use and maintenance of a private swimming pool will involve automatic home swimming pool cleaning machines. At night or when no one is using the swimming pool, an automatic swimming pool cleaning machine will be activated to patrol the bottom surface and side walls, to clean debris in the pool and dirt on the side walls. Some of the cleaning machines are driven by a motor or employs a motor to pump water. However, electrical circuits and elements for controlling the motor or other electronic devices are required to be kept underwater in a sealed box. Thus, the sealed box should be waterproof to protect the electronic devices therein.
In the prior art, the boxes used for the equipment are made of plastic. A piece of metal is installed therein to contact with the electrically controlled bottom board and to extend to the outside of the plastic box to eliminate heat while submerged in water.
In the prior art, the plastic box includes a wire that enters the box and a wire that exits the box. In manufacturing, the electronic devices are placed inside the box and then are sealed it to prevent water from leaking. Actually this kind of apparatus is formed by a box component made of two pieces of plastics. The joint surface between the two pieces of plastic will age and with age over a long period of time will leak and the water leakage will damage the electronic devices therein.
U.S. Pat. No. 5,183,966 discloses a water-proof connection apparatus for an underwater cable for protecting the cable from being affected by sea water. The configuration of the patent cannot protect the circuit board with more restrict waterproof requirements. If the circuit board leaks when being using for a long time, a user cannot estimate the status inside the circuit board without opening the box.
Chinese patent CN 03110486.X discloses a pool cleaning machine, that is electrically controlled or by other controlling circuit devices. However, this patent does not disclose any waterproof method or apparatus to protect the circuit apparatus in the machine.
According to the boxes for a motherboard of an electrically controlled circuit in a traditional cleaning machine, the following defects should be overcome:
The problem of waterproofing and the corruption between the heat elimination metal and the plastic box. If a sealant is applied, as the thermal expansion coefficients of a metal piece and sealant are different. After use over a long time, iterative hot/cold will damage the sealability of the metal. If a sealant is applied between the metal piece and plastic box, when the cleaning machine is used iteratively, erodibility of the water accumulated in the gap will increase. Pools are often sanitized by chlorine. Thus, the water contains a quantity of chlorine ions. When the cleaning machine is pulled out of the pool, part of the water that contains chlorine ion will stay in the gap between the pad and metal. After water is volatilized, the content of the chlorine ions will increase significantly, and after a long time using the machine, the chlorine ions will corrupt the metal, thus damaging the seal.
No matter in what condition or for what reason, in the traditional designs if the seal of the motherboard is damaged due to a leak, the damage to the components on the motherboard are quickly known by the user. However, at this time, it is too late to prevent the damage.
In the traditional designs, even by certain instruments, it is impossible to check to determine if the seal is airproof and in good condition to protect the motherboard. Not only are sensitive instruments required to detect the minor leakage, but also after the detection is finished, it is impossible to detect the sealing ability of the probe's entrance into the box.
The problems relate to the design of the seal on the motherboard. Because the rigidity of plastic box is limited, the seal will be affected by outside force and heat. The market available of waterproof pads or sealants designed with assuming the rigidity and level of the conjugating components continue to change. It is not always a good idea that the sealants cannot match with the special environmental applications.
Electronic controlling components that are affected by dampness will affect the natural operation of the cleaning machine, such deviations will occurs when reversing or changing the ongoing direction of the machine. Without knowing the condition of whether the controlling components were affected with dampness or not, it is difficult to proceed with maintenance and cleaning of the machine.
The problem of humidity relates to the moisture in the air. In an aerographic study, there are different methods for calculating humidity, including vapor pressure in the air. The pressure value is proportional to the content of vapor in air. Another calculation method is a mixing ratio, which is calculating the weight (in grams) of vapor in 1 liter of dry air. Two seldom applied methods relate to specific humidity, which is the ratio of the weight of vapor (in grams) as comparing with the weight of wet air (that is, both dry air and vapor) (in kilograms) and to absolute humidity, which is the weight (in grams) of vapor in 1 cubic meter of dry air. In modern aerographic studies, a method of relative humidity is widely applied. Relative humidity is the ratio of vapor pressure comparing with saturated vapor pressure. Saturated vapor pressure is the pressure that the largest amount of vapor in the air under certain temperatures. More specifically, in a balanced situation, the number of water molecules vaporized in the air from water that is approximately equal to the number of water molecules frozen in the air.
A hygrometer is the most accurate instrument for measuring absolute and relative humidity in modem technology, the earliest inventor is an English meteorologist, John F. Daniell (1790-1845) who invented a dew-point hygrometer, which is referred to as a Daniell hygrometer by meteorologists. The hygrometer is formed by two glass balls connected with a glass tube. The common hygrometer nowadays is a psychrometer, which is formed by two parallel thermometers, one for measuring air temperature, the other for measuring wet-bulb depression in wet cotton. A comparison table is provided to check the relative humidity detected by these two thermometers. Another commonly used hygrometer is a hair hygrometer which utilizes the concept of human hair flexing according to changes in humidity. The hair hygrometer may also be designed as a hygrograph for recording relative humidity automatically.